Sailing Downwind in strong winds

Moderator: GreenLake

Sailing Downwind in strong winds

Postby DigitalMechanic » Tue Nov 17, 2015 8:29 am

I think I have had my paranoia's about capsizing backward in my head. I was originally more scared about sailing over trimmed going upwind, due to the boat naturally wanting to heel more. However, I guess it is pretty good at self righting in that sail position. My friend also was telling me that it is downwind that you need to worry about. It makes sense, when reaching the boom is out there, and like you said... no way to de-power once it touches the water. Past letting the jib out, I think that if you sailed with a lot of vang on, a quick release may give you a couple more inches to raise the boom if getting knocked down. But I am not sure that is a good thing. Would't that power the main back up? Parachute effect?
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Re: Mainsheet setup and Purchase System

Postby talbot » Tue Nov 17, 2015 1:30 pm

In the situation we're talking about--strong winds--you would already have the vang maxed out. The tight vang flattens the sail and pulls the draft farther aft. That spills some wind that you don't need (just makes the boat tip) and when you're going upwind, it gives the sail a better shape in relation to the airflow.

But as far as avoiding a capsize, you still need to be able to release the jib. Your friend is right that going downwind has some special concerns, expecially when the wind is gusty. Everyone worries about a full gybe, where the wind gets in front of the main and flips it across the boat. But I've had as many issues with getting panicked by a gust (see earlier note about sissyness) and rounding up too quickly from a deep reach. From that point of sail, you have to round up a long way before the wind stops pushing the boat over. And the boat is sailing so fast in that situation it feels like it could roll from its own momentum.

I had to learn it was like recovering from a skid in a car. ("Skid" is a term we use up here when it "snows." Um . . . trying to relate . . . imagine hitting an alligator on smooth pavement covered with palmetto leaves wet with spring-break beer spill.) Anyway, when you are in a deep reach and are hit by a gust, you usually turn down wind for a second. Even if it puts more pressure on the sail, that pressure is from the stern, not from the side, so the boat settles back down.

Man, I've got to step out of this forum. I'm supposed to be at work, and all this talk about sailing is making it really hard to concentrate. I would be more focused if I were cruising porn sites.
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Re: Mainsheet setup and Purchase System

Postby DigitalMechanic » Tue Nov 17, 2015 2:15 pm

The tight vang flattens the sail and pulls the draft farther aft.


I think I got that. Unfortunately the vang on my boat is kind of difficult to pull. I could not tighten it too much when reaching. Upgrading it is on my todo list. Actually one of my core questions was about how much purchase to add to the DS II vang. I am being presumptuous, but the much talked about 20:1 on a DS II boat is probably not necessary? I currently have the 40 year old original 3:1 that came with the boat.

When we were talking about heeling to much on a broad reach, as you described the boom hitting the water, I am with you on letting the jib out. But my "curious" question was what about releasing the vang as well. Wouldn't that allow the boom to pop up further above the water, lifting the sail and spilling wind?

Everyone worries about a full gybe, where the wind gets in front of the main and flips it across the boat.


Now that I am thinking about it, it seemed like the closer we sailed to a "run", he seemed to keep a hand on the part of the mainsheet between the boom and centerboard trunk. I imagine that he was trying to sense whether or not the wind was going to shift and bring the boom across unexpectedly? I know aside from that he always had a hand on that part of the sheet during a tack or gybe to help ease the boom across the boat. I had actually started doing that prior to this last sail (at least on gybes). I have had the boom violently move from one side of the boat to the other on a gybe... It's not so fun, lol.

From that point of sail, you have to round up a long way before the wind stops pushing the boat over. And the boat is sailing so fast in that situation it feels like it could roll from its own momentum.


Does not sound like fun either. Well maybe fun as long as the boat does not capsize, kind of like a "wheely" and "donut" in a car on oil slicked pavement... but no brakes... Dukes of Hazard, lol. Sounds dangerous... I will make sure not to try that (at least not on purpose) :wink:

imagine hitting an alligator on smooth pavement covered with palmetto leaves wet with spring-break beer spill.


I get the Florida relation, lol. You could of just said redneck mudding his pickup truck (there will still probably be alligators, palmetto leaves, and spilt beer in that scenario too). :D
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Re: Mainsheet setup and Purchase System

Postby K.C. Walker » Fri Nov 20, 2015 11:10 am

Sailing downwind in strong or gusty winds can be a lot of fun (within reason). Obviously, you need to work up to it. The trick is, as Talbot said, turn downwind. If you think of it as sailing yourself under the rig it can become pretty second nature. Even before you get to a run, as in a deep reach, you are already starting to blanket the jib with the main and that reduces power greatly.

With the boom out and heeled over your center of effort is way out there, so the boat really wants to round up. To counter this and get it to turn down you need to move back and hike out. You don’t want to stall the rudder or let it loose grip! That’s a likely way to go over as the boat rounds up and takes on even more power. The rudder technique is not to just pull it over but to jerk it a couple of times quickly. You’ll get the feel for when it’s starting to lose grip and that’s the time to bring it back to midship and then jerk it again to windward. Oh yeah, and don’t pull your center board all the way up! You need something to turn against.

This is in the territory of the boat planing. Once you get the boat up on a plane it actually becomes easier to control, though the adrenaline factor is definitely up. The rudder will respond much quicker when the boat’s going that fast and with the boat going that fast the apparent wind is much less. As you have turned down, blanketing the jib, and reducing the apparent wind the boat might start to come off plane, that’s the time to start playing with heading back up a bit to pick up some more power, as we like that adrenaline rush!

And do I think 20:1 vang is too much for a daysailer? Absolutely not! Think it’s perfect!
KC Walker, DS 1 #7002
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Re: Mainsheet setup and Purchase System

Postby talbot » Fri Nov 20, 2015 2:06 pm

OK, this might be getting geeky . . . .
I always hear the racers talking about getting weight forward going downwind. Apparently the DS and other planing hulls like Thistles are faster if sailed flat fore and aft as well as side to side.
So I'm not sure how to take the advice to move aft off the wind. The topic in the last post was steering, not speed, so I'll guess that the interpretation is something like this:

  • If you are more concerned about steering, as in rounding up uncontrollably, move your weight aft, which tends to make the boat weathervane down wind, countering the usual weather helm. But dragging the stern also slows the boat down.
  • If you are more concerned about speed, and have the steering skills to control the boat, move forward to keep the hull flat. Keeping in mind that if you lose control with the boat on a plane, you might get very wet.

Is that correct?
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Re: Mainsheet setup and Purchase System

Postby GreenLake » Fri Nov 20, 2015 4:35 pm

I always thought fore and aft balance depended on whether you were sailing in displacement mode or planing.

I know local racers that will put someone way up front in light airs (not on a DS but another dinghy of similar size and with a planing hull). That seems to be competitive.

I also know that when I sit too far back (or load the transom down with gear, such as motors) the DS will drag its stern trough the water. That is definitely slow (in displacement mode).

For powerboats you have trim tabs so that you can dial in the correct hull attitude for fastest planing or semi-planing. Here, bow down as well as bow up are to be avoided, in favor of a happy medium (bow slightly up).

Add to that, that going downwind the rig will try to lever the boat bow down, and at some point (stronger winds) you'll eventually will want to give some counter balance. I personally don't have the experience with enough downwind in stronger airs to have that all sorted, but these different considerations may explain why you end up getting some seemingly contradictory suggestions.

Also, about sailing planing hulls flat. There's a light wind (low speed) regimen, where wetted surface dominates friction. In those conditions some boats sail better when heeled (makes the hull narrower). Lasers will stick their boom up in that situation which raises the average height across the sail area into faster winds (slow winds are laminar, with speed gradually rising with height) and balancing the area better above the boat than with the boom the other direction.

I've seen people do this on dinghies that are more like the DS, but ligher, but don't know whether it's considered a move that pays off in a DS.
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Re: Sailing Downwind in strong winds

Postby K.C. Walker » Fri Nov 20, 2015 5:31 pm

Moving forward and letting the boat heel downwind is all about light air and wetted surface. I don’t race so I have not paid attention to whether this is faster in a daysailer. Likely this would produce weather helm and that’s slow. I’m pretty sure that the racing guys say that keeping it flat is fastest.

I thought I was commenting on heavy gusty air concerns about capsizing. Being that the daysailer is a relatively beamy boat with a short rudder, moving back and hiking out is to keep as much rudder in the water as possible. Pretty likely if you are heeled over in strong air you’re not planing and likely plowing with the bow down and dragging the rudder due to weather helm (and it’s likely close to losing grip). Once you get the boat under the rig (sailing flat) and it starts planing you may not need to hike out as much and maybe not be as far back. If you are feeling weather helm you need to be hiking harder. Once the boat starts planing the effective waterline is shorter and back. You want the boat mostly riding on the flat parts of the bottom, so you want it slightly bow up.

This all applies to the standard suit of sails, but I do get to do this more often because of using the UPS gennaker, being that this happens at lower wind speeds for me.
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Re: Sailing Downwind in strong winds

Postby GreenLake » Fri Nov 20, 2015 7:20 pm

Yes, that agrees with what I thought. One of our local venues tends to run to lighter air at the time of the weekly race and that's where I get to observe what the other sailors do.
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Re: Sailing Downwind in strong winds

Postby DigitalMechanic » Fri Nov 20, 2015 10:36 pm

This is all great info guys. I really appreciate it. You are making me nervous to sail downwind now, lol.

So if I understand correctly... down wind, when overpowered try and turn the stern into the wind even more so you get even closer to a dead run (and slowly fall back off)? This powers the sail up even more, but flattens the boat (which protects the boom), allowing opportunity to ease the main. To make sure I am visualizing this correctly in my head... the weather helm will be pulling the tiller away from me (trying to round up), and I would need to pull it in to try and put the wind more on the center of the stern?

If unsuccessful, this is where the accidental jibe comes in that Talbot mentioned? The "mega round up", trying to spin the boat 180 degrees because the rudder loses footing allowing the wind to freely rotate the boat on the centerboard?

Conversely, the natural reaction of letting the mainsheet out to de-power the sail first will cause the boat to heel even more, causing the boom to potentially hit the water and capsize? However, releasing the jib will help flatten the boat if there is not enough time do "All the above"?

Sorry, my vocabulary is either not salty enough yet, or I am retarded, but probably a little of both, lol.
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Re: Sailing Downwind in strong winds

Postby Interim » Mon Nov 30, 2015 12:53 pm

DigitalMechanic wrote:This is all great info guys. I really appreciate it. You are making me nervous to sail downwind now, lol.
.


Ellen MacArthur described a time when she was racing to be a major storm across the southern ocean, and was in 50' waves and gale force winds. She said to imagine driving through a neighborhood at 30mph. You feel in control, and safe. Now increase to 50, 60, 80mph. You feel like you are on the edge of control. Now take away the brakes, and turn off the lights.

Granted, I can't compare my little DS II to her big trimaran, or my little lake to the southern ocean, but there are certainly times when my spot on the spectrum between skill and luck shifts too far and I am surprised that I stay upright.

--john
1979 DSII
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Re: Sailing Downwind in strong winds

Postby DigitalMechanic » Fri Dec 04, 2015 12:31 am

I hear you on that one. I believe she said something about no more windshield wipers as well. Completely blind, no control, and in total chaos at that point...

I would probably be about there in 15-20 mph wind, lol. I am just learning so I will stick to the 12-13mph and under days for now.
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Re: Sailing Downwind in strong winds

Postby GreenLake » Fri Dec 04, 2015 6:31 am

Once you know where everything is on your boat, and there's a bit of moonlight, star shine, or even skyshine from some nearby metropolis, you'll enjoy a bit of night sailing. It can be magical. Best with gentle breezes for a start. Some people really don't function in low light levels, or cannot stay awake, but as a confirmed night owl the latter isn't a problem and the former, so far, has proven a non-issue as well. When you're ready, or just curious, let's start a new thread on that topic.
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Re: Sailing Downwind in strong winds

Postby GreenLake » Mon Dec 07, 2015 5:59 pm

That other thread is now split off and can be found under "Fleets/Locations" as "Sailing around Jacksonville, FL".

Generally, if the discussion veers to a very different topic, best to make a new thread.
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Re: Sailing Downwind in strong winds

Postby druidae1492 » Mon Jun 19, 2017 9:26 pm

GreenLake wrote:Once you know where everything is on your boat, and there's a bit of moonlight, star shine, or even skyshine from some nearby metropolis, you'll enjoy a bit of night sailing. It can be magical. Best with gentle breezes for a start. Some people really don't function in low light levels, or cannot stay awake, but as a confirmed night owl the latter isn't a problem and the former, so far, has proven a non-issue as well. When you're ready, or just curious, let's start a new thread on that topic.


I love a nice midnight sail in the San Juan Islands. SO peaceful, and I have unusually good night vision. :) It also helps knowing the local area and all the islands and rocks.
We can not control the weather, we can only adjust our sails.
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Re: Sailing Downwind in strong winds

Postby fatjackdurham » Wed Aug 02, 2017 4:17 pm

The title of this topic reminded me of an experience at summer camp. An extended squall had blown in and an O'Day Javelin somehow slipped it's mooring and got blown down a bay. Me and a Danish sailing instructor took a Sunfish out to go get it. The winds were sooooo strong, that even with the centerboard up, and both of us sitting on the fantail we couldn't keep the bow above the water running down wind. We cartwheeled the boat end over end. We had to just let the sail loose to luff downwind and we still were planing all the way down.

That Javelin sailed superbly, though, reefed in the high winds with a storm jib. We towed the Sunfish back (taking our time because it was the best sailing we had had that summer) and all was well.
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